The present invention is related to electronic circuitry. More particularly, the present invention is related to systems for regulating the voltage level of a signal.
The last few decades have witnessed unprecedented growth in the use of integrated electronic circuitry. This rapid growth has been accompanied by a steadily decreasing physical size and a steadily increasing complexity of circuits. Physically smaller circuits are advantageous in that they may be used in many applications that would have been impractical or even impossible in the past. Also, decreasing circuit size has led to smaller amounts of materials required for fabrication, which drives down costs and decreases the price/performance ratio of circuits.
Designing and building circuits on small physical scales presents numerous technological challenges. For example circuit behavior can deviate significantly from the ideal as feature sizes shrink. On smaller scales, signal wires on a chip can couple to neighboring signal wires by both capacitive and inductive means. When these wires are used to transfer signals that have very fast edge rates these coupling mechanisms can cause distortions in the signals of neighboring wires that in turn can cause logic failures. Such effects are becoming particularly frequent on highly dense, highly miniaturized circuits such as very large scale integrated (xe2x80x9cVLSIxe2x80x9d) circuits used on chips and the like.
One of the logic failure distortions that can result from improperly coupled signal wires is deviation of a logic signal outside of its normal range of voltage levels. This deviating signal may be misinterpreted by a logic gate as a logic xe2x80x98onexe2x80x99 level instead of a logic xe2x80x98zeroxe2x80x99 or vice versa. In extreme cases, the signal deviation may be so excessive so that the resulting voltage level is such that it can cause permanent damage to the circuit.
The prior art has proposed methods for ensuring and maintaining circuit signal quality. For example, one prior art method comprises carefully controlling the use of line widths and spaces when designing an integrated circuit. Through such control, a circuit designer can, in theory, control the worst-case amount of capacitive or inductive coupling to neighboring wires and thus insure worst-case bounds of signal behavior. While this practice may be practical for simple circuits, the method has proven much more difficult to use for circuits of appreciable size and complexity. Also, controlling line widths and spaces to control coupling problems often results in using wire resources in less than the available density. Further, manufacturing tolerances for highly miniaturized circuits may additionally limit the usefulness of this method. Another prior art method involves judicious control of location of signals to minimize the routing of critical signals near to one another. Unfortunately, this method also has proven impractical for use with circuits of an appreciable size and complexity due to the enormous resources required for mapping the physical location and modeling the operation of the various signals and components in such circuits.
Unresolved needs in the art therefore exist.
The present invention is directed to a system for controlling the level of an electrical signal between a high and a low level. A system embodiment of the invention generally comprises a first switch connected to the signal and connected to at least a high voltage source, and a second switch connected to the signal and connected to at least a low voltage source. The high voltage source is substantially equal to the high level, while the low voltage source is substantially equal to the low level. One of the switches is biased to an on position when the signal is less than the low level whereby the signal will increase in voltage until it is at least substantially equal to the low level. The other of the switches is biased to an on position when the signal is greater than the high level whereby it will decrease in voltage until it is substantially equal to the high level.
The present invention thereby provides an elegant solution to many unresolved problems in the art. As an example, systems of the invention can be used on integrated circuits to insure that signals remain within a desired range, with potential cross-signal capacitance/inductance failures significantly reduced. Further, use of embodiments of the invention provides low cost alternative that can reduce or even eliminate the need to use cumbersome and intensive prior art methods of avoiding cross-signal capacitance/conductance failures.
The above brief description sets forth broadly some of the features and advantages of the present disclosure so that the detailed description that follows may be better understood, and so that the present contributions to the art may be better appreciated. There are, of course, additional features of the disclosure that will be described hereinafter that form the subject matter of the claims appended hereto. In this respect, before explaining embodiments of the disclosure in detail, it is to be understood that the disclosure is not limited in its application to the details of the construction set forth in the following description or illustrated in the drawings. The present invention may provide additional embodiments, as will be appreciated by those knowledgeable in the art. Also, it is to be understood that the phraseology and terminology employed herein are for description and not limitation.